This paper concludes that letters are highly mediated by criteria internal to the newsroom. Participant observation in the chosen newspapers showed that there are specific rules governing the letters to the editor column – for instance, the letter author must write about a newsworthy and up-to-date theme or event, a (“hot topic”), already established in the journalistic agenda; besides that, his text has to be well written and short. Also, editors use an “idiom of insanity” (Wahl-Jorgensen, 2002) when they refer to some contributors to the section as “crazy”, such is, the people that lack the rationality that is necessary for public deliberation. This paper underscores the power of the news media in selecting letters to the editor, as they control the last word and exclude certain sources from the public conversation.